Digital broadcasting receiver and channel information registration processing method in digital broadcasting receiver

ABSTRACT

Disclosed in a digital broadcasting receiver comprising first means for performing pre-scan processing for successively tuning in on channels previously set, to examine whether or not a received signal on each of the channels is of a predetermined quality or more, and temporarily registering the channel numbers of the channels on which the received signals are of the predetermined quality or more in a storage device as receivable channel candidates, and second means for performing normal scan processing for successively tuning in on the receivable channel candidates temporarily registered in the storage device by the first means, to acquire and register necessary channel information.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a digital broadcasting receiverfor receiving digital TV broadcasting and digital audio broadcasting,and a channel information registration processing method in the digitalbroadcasting receiver.

[0003] 2. Description of the Prior Art

[0004] In conventional television broadcasting receivers, channelinformation such as a receivable channel number and service informationhave been registered in the receiver by making a channel scan (a search)for each channel. Conventionally, within a range of channels which canbe received by a tuner, all the channels including the channel on whichno programs are actually broadcast have been successively searched forthe channel information.

[0005] In order to acquire the service information, it is necessary towait until a demodulation/FEC (Forward Error Correction) circuit islocked. When the channel on which no programs are actually broadcast issearched, the demodulation/FEC circuit is not locked. Therefore, it hasbeen conventionally judged whether or not the demodulation/FEC circuitis locked for a predetermined time period, to search the subsequentchannel if the demodulation/FEC circuit is not locked. Conventionally,it has been thus judged whether or not the demodulation/FEC circuit isalso locked with respect to the channel on which no programs areactually broadcast. Accordingly, it takes much time to register thechannel information.

SUMMARY OF THE INVENTION

[0006] An object of the present invention is to provide a digitalbroadcasting receiver capable of shortening a time period required toregister channel information, and a channel information registrationprocessing method in the digital broadcasting receiver.

[0007] A digital broadcasting receiver according to the presentinvention is characterized by comprising first means for performingpre-scan processing for successively tuning in on channels previouslyset, to examine whether or not a received signal on each of the channelsis of a predetermined quality or more, and temporarily registering thechannel numbers of the channels on which the received signals are of thepredetermined quality or more in a storage device as receivable channelcandidates; and second means for performing normal scan processing forsuccessively tuning in on the receivable channel candidates temporarilyregistered in the storage device by the first means, to acquire andregister necessary channel information.

[0008] The pre-scan processing may be performed a plurality of number oftimes in the first means. It is preferable that the pre-scan processingis performed in a state where the gain of an automatic gain controlamplifier in a tuner is fixed.

[0009] It is judged in the first means whether or not the receivedsignal is of the predetermined quality or more on the basis of judgmentwhether or not received power is more than a predetermined value, forexample.

[0010] Examples of the channel information include a receivable channelnumber, service information in the case of a channel in digitalbroadcasting, and a distinction between the channel in digitalbroadcasting and a channel in analog broadcasting.

[0011] A channel information registration processing method in a digitalbroadcasting receiver according to the present invention ischaracterized by comprising a first step of performing pre-scanprocessing for successively tuning in on channels previously set, toexamine whether or not a received signal on each of the channels is of apredetermined quality or more, and temporarily registering the channelnumbers of the channels on which the received signals are of thepredetermined quality or more in a storage device as receivable channelcandidates; and a second step of performing normal scan processing forsuccessively tuning in on the receivable channel candidates temporarilyregistered in the storage device in the first step, to acquire andregister necessary channel information.

[0012] The pre-scan processing may be performed a plurality of number oftimes in the first step. It is preferable that the pre-scan processingin the first step is performed in a state where the gain of an automaticgain control amplifier in a tuner is fixed.

[0013] It is judged in the first step whether or not the received signalis of the predetermined quality or more on the basis of judgment whetheror not received power is more than a predetermined value, for example.

[0014] Examples of the channel information include a receivable channelnumber, service information in the case of a channel in digitalbroadcasting, and a distinction between the channel in digitalbroadcasting and a channel in analog broadcasting.

[0015] The foregoing and other objects, features, aspects and advantagesof the present invention will become more apparent from the followingdetailed description of the present invention when taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a block diagram showing the configuration of a digitalbroadcasting receiver;

[0017]FIG. 2 is a timing chart showing an example of a receivingspectrum in a UHF-TV band;

[0018]FIG. 3 is a timing chart showing a signal waveform after detectionin a case where a channel scan is made;

[0019]FIG. 4 is a timing chart showing a signal indicating whether ornot a channel tuned in on is receivable;

[0020]FIG. 5 is a timing chart showing a demodulation locking signalindicating that a digital broadcast wave is normally received anddemodulated;

[0021]FIG. 6 is a timing chart showing a flag indicating that a receivedsignal is an analog broadcast wave; and

[0022]FIG. 7 is a flow chart showing the procedure for channelinformation registration processing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] An embodiment of the present invention will be described.

[0024]FIG. 1 illustrates the configuration of a digital broadcastingreceiver.

[0025] In FIG. 1, reference numeral 1 denotes a receiving antenna.Reference numeral 2 denotes a tuner for tuning in on an RF (RadioFrequency) signal from the antenna 1 and converting the RF signal tunedin on into an IF (Intermediate Frequency) signal.

[0026] Reference numeral 3 denotes an initial-stage amplifier. Referencenumeral 4 denotes an AGC (Automatic Gain Control) amplifier whose gainis variable by a control voltage from the exterior. Reference numeral 5denotes a down converter for converting the received RF signal into anIF signal that is a difference frequency signal between a localfrequency signal generated in a voltage controlled oscillator 6 and thereceived RF signal. Reference numeral 7 denotes a PLL (Phase-LockedLoop) circuit for controlling the frequency of an output signal of thevoltage controlled oscillator 6 to a desired predetermined frequency bychannel selection data from a CPU 21. Reference numeral 8 denotes a D/A(Digital-to-Analog) converter for generating a gain control voltage ofthe AGC amplifier 4 by control data from the CPU 21.

[0027] Reference numerals 9, 11, and 17 denote intermediate frequencyamplifiers. Reference numeral 10 denotes a band pass filter forextracting the IF signal from a signal whose frequency has been changed(an output signal of the intermediate frequency amplifier 9). Referencenumeral 12 denotes an A/D (Analog-to-Digital) converter for convertingthe IF signal outputted from the intermediate frequency amplifier 11into digital data. Reference numeral 13 denotes a demodulation/FECcircuit for demodulating the received signal which has been convertedinto the digital data by the A/D converter 12 and correcting errors.Reference numeral 14 denotes an MPEG (Motion Picture Expert Group)decoder for converting a transport stream in an MPEG format which hasbeen demodulated by the demodulation/FEC circuit 13 into a base bandsignal.

[0028] The demodulation/FEC circuit 13 outputs a locking signal (d) whenit normally receives a digital broadcast wave. Further, thedemodulation/FEC circuit 13 comprises the function of judging whether ornot the received broadcast wave is an analog broadcast wave on the basisof judgment whether or not a horizontal synchronizing signal of ananalog modulated wave can be extracted. The demodulation/FEC circuit 13outputs an analog broadcast wave flag (c) when it normally receives theanalog broadcast wave.

[0029] Reference numeral 15 denotes a base band video signal outputterminal. Reference numeral 16 denotes a base band audio signal outputterminal. Reference numeral 18 denotes a detection circuit for detectingthe IF signal outputted from the intermediate frequency amplifier 17.Reference numeral 19 denotes a comparator for comparing the level of theIF signal, which has been detected, obtained by the detection circuit 18with a reference voltage in order to judge whether or not a channeltuned in on is receivable. Reference numeral 20 denotes a D/A converterfor converting the data from the CPU 21 into a voltage to generate thereference voltage of the comparator 19.

[0030] Reference numeral 21 denotes a CPU. Reference numeral 22 denotesa memory. Reference numeral 23 denotes an operation unit operated by aviewer. Reference numeral 24 denotes a remote control receiver forreceiving a signal from a remote control (not shown) and issuing acommand to the operation unit 23. Reference numeral 25 denotes an SI(Service Information) decoder for demodulating service informationmultiplexed on each physical channel.

[0031]FIG. 2 illustrates an example of a receiving spectrum in a UHF(Ultrahigh Frequency)-TV band.

[0032]FIG. 3 illustrates a signal waveform (a voltage waveform of asignal (a)) after the detection in a case where a channel scan is made.

[0033]FIG. 4 illustrates a signal indicating whether or not a channeltuned in on is receivable, that is, an output signal (a signal (b)) ofthe comparator 19.

[0034]FIG. 5 illustrates a demodulation locking signal (a signal (d))indicating that a digital broadcast wave is normally received anddemodulated.

[0035]FIG. 6 illustrates a flag indicating that a received signal is ananalog broadcast wave, which is a waveform of a signal (c) outputtedfrom the demodulation/FEC circuit 13.

[0036] In a case such as a case where an antenna or a receiver isinstalled or a case where new broadcasting stations which can receivesignals are opened, it is necessary to previously examine thebroadcasting station in an area where the receiver is installed andregister in the receiver channel information such as a receivablechannel and service information in order for a viewer to easily selectthe receivable channel. In registering the channel information, theviewer turns on the power to the receiver, and selects a channel scanmode by an initial menu in the operation unit 23.

[0037]FIG. 7 shows the procedure for channel information registrationprocessing performed by the CPU 21 in a case where the channel scan modeis selected.

[0038] The channel information registration processing comprisespre-scan processing and normal scan processing. Description is firstmade of the pre-scan processing.

[0039] When the channel scan mode is selected, the CPU 21 feeds data tothe D/A converter 8 such that the gain of the AGC amplifier 4 reachesits maximum (step 1). Further, the CPU 21 feeds data to the D/Aconverter 20 in order to feed to the comparator 19 a reference voltagefor judging whether or not a channel tuned in on is receivable (step 2).

[0040] Furthermore, the CPU 21 sets an initial value of the channeltuned in on (step 3). As the initial value, the minimum value in achannel range, that is, Channel 14 is set in the case of U.S. UHF. Inorder to tune in on the set channel, channel selection data is fed tothe PLL circuit 7 (step 4).

[0041] A radio wave received in the antenna 1 is amplified by theinitial-stage amplifier 3 in the tuner 2, is further amplified by theAGC amplifier 4 whose gain has been set to its maximum by an instructionfrom the CPU 21, and is then fed to the down converter 5. A local signalgenerated in the voltage controlled oscillator 6 is fed to the downconverter 5.

[0042] An output signal of the down converter 5 is fed to the band passfilter 10 through the amplifier 9. An IF signal on a desired channeltuned in on is outputted from the band pass filter 10. The IF signal isamplified by the amplifier 17, and is then fed to the comparator 19through the detection circuit 18. In the comparator 19, an outputvoltage of the detection circuit 18 and the reference voltage outputtedfrom the D/A converter 20 are compared with each other in order to judgewhether or not the channel tuned in on is receivable.

[0043] A high-level signal indicating that the channel tuned in on isreceivable is outputted from the comparator 19 when the output voltageof the detection circuit 18 is more than the reference voltage, and alow-level signal indicating that the channel tuned in on is notreceivable is outputted from the comparator 19 when the output voltageof the detection circuit 18 is not more than the reference voltage. TheCPU 21 judges whether or not the channel tuned in on is receivable onthe basis of the output of the comparator 19 (step 5).

[0044] The CPU 21 writes, when it judges that the channel tuned in on isreceivable, the channel number of the channel into the memory 22 as areceivable channel candidate (step 6), and then updates the channelnumber of the channel tuned in on to the subsequent channel number (step7). On the other hand, the CPU 21 updates, when it judges that thechannel tuned in on is not receivable, the channel number of the channeltuned in on to the subsequent channel number without writing the channelnumber into the memory 22 as a receivable channel candidate (step 7).

[0045] The CPU 21 judges whether or not the channel number which hasbeen updated in the step 7 exceeds its upper limit value (“83” in thisexample) (step 8). Unless the updated channel number exceeds the upperlimit value, the program is returned to the step 4, to perform the sameprocessing. When the updated channel number exceeds the upper limitvalue, the pre-scan processing is terminated, to proceed to the normalscan processing.

[0046] When a digital broadcast wave of a predetermined quality or moreis received, a locking signal (a signal (d) in FIG. 1) indicating thatdemodulation is possible is outputted from the demodulation/FEC circuit13. In the pre-scan processing, however, it is judged whether or not thechannel tuned in on is receivable without examining the locking signal.In the pre-scan processing, a waveform as shown in FIG. 4 is obtainedfrom the comparator 19.

[0047] The normal scan processing will be described.

[0048] In the normal scan processing, the CPU 21 releases the fixing ofthe gain of the AGC amplifier 4 (step 9). Consequently, the gain of theAGC amplifier 4 is controlled to the most suitable gain in conformitywith the level of a received signal, as at the time of normal receiving.

[0049] The CPU 21 reads out one of the channel numbers of the receivablechannel candidates which have been stored in the memory 22 by thepre-scan processing (step 10). In the examples shown in FIGS. 3 and 4,Channels 14, 16, 18, 19, . . . , 78, 80, 81, 83 are stored in the memory22 as receivable channel candidates. Accordingly, Channel 14 is firstread out.

[0050] The CPU 21 feeds data to the PLL circuit 7 in order to tune in onthe channel whose channel number has been read out of the memory 22(step 11). When the channel is tuned in on, an IF signal correspondingto the channel tuned in on is outputted from the tuner 2 and isconverted into digital data by the A/D converter 12. The digital data isthen fed to the demodulation/FEC circuit 13, where it is subjected todemodulation and error correction.

[0051] When the digital broadcast wave is normally received, asdescribed above, the locking signal (d) is outputted from thedemodulation/FEC circuit 13. When the analog broadcast wave is normallyreceived, an analog broadcast wave flag (c) is outputted from thedemodulation/FEC circuit 13.

[0052] The CPU 21 judges whether or not the locking signal (d) isoutputted from the demodulation/FEC circuit 13 (step 12), whether or notthe analog broadcast wave flag (c) is outputted from thedemodulation/FEC circuit 13 (step 13), and whether or not apredetermined time period has elapsed since the channel was tuned in onin the step 11 (step 14).

[0053] The CPU 21 decodes, when it receives the locking signal (d) fromthe demodulation/FEC circuit 13 (YES in step 12), service informationfrom demodulation data by the SI decoder 25 (step 15), and registers inthe memory 22 the decoded service information as service informationcorresponding to the channel tuned in on (step 16). Thereafter, theprogram proceeds to the step 18.

[0054] The CPU 21 registers, when it receives the analog broadcast waveflag (c) from the demodulation/FEC circuit 13 (YES in step 13), the factthat the channel tuned in on is a channel in analog broadcasting isregistered in the memory 22 (step 17). The program proceeds to the step18.

[0055] When the CPU 21 judges that a predetermined time period haselapsed since the channel was tuned in on in the step 11 withoutreceiving the locking signal (d) and the analog broadcast wave flag (c)from the demodulation/FEC circuit 13, the program proceeds to the step18.

[0056] In the step 18, it is judged whether or not the processing in thestep 10 and the subsequent steps is performed with respect to all thereceivable channel candidates in the memory 22. When the processing inthe step 10 and the subsequent steps is not performed with respect toall the receivable channel candidates in the memory 22, the channelnumber is updated to the channel number of the subsequent receivablechannel candidate (step 19). Thereafter, the program is returned to thestep 10.

[0057] When the processing in the step 10 and the subsequent steps isperformed with respect to all the receivable channel candidates in thememory 22, the channel numbers of the receivable channel candidateswhich have been stored in the memory 22 in the pre-scan processing areerased (step 20). Thereafter, the normal scan processing is terminated.

[0058] Although in the above-mentioned embodiment, the pre-scanprocessing is performed only once, the pre-scan processing may beperformed a plurality of times. When the pre-scan processing isperformed a plurality of times, it can be judged whether or not achannel is a channel which is judged to be stably receivable or achannel, inferior in signal receiving quality, whose receiving levelchanges with time by fading or the like even if it is judged to be areceivable channel candidate. With respect to the channel inferior insignal receiving quality, it is possible to shorten the predeterminedtime period in the step 14 at the time of the normal scan processing.

[0059] Although the present invention has been described and illustratedin detail, it is clearly understood that the same is by way ofillustration and example only and is not to be taken by way oflimitation, the spirit and scope of the present invention being limitedonly by the terms of the appended claims.

What is claimed:
 1. A digital broadcasting receiver comprising: firstmeans for performing pre-scan processing for successively tuning in onchannels previously set, to examine whether or not a received signal oneach of the channels is of a predetermined quality or more, andtemporarily registering the channel numbers of the channels on which thereceived signals are of the predetermined quality or more in a storagedevice as receivable channel candidates; and second means for performingnormal scan processing for successively tuning in on the receivablechannel candidates temporarily registered in the storage device by thefirst means, to acquire and register necessary channel information. 2.The digital broadcasting receiver according to claim 1, wherein thepre-scan processing is performed a plurality of number of times in thefirst means.
 3. The digital broadcasting receiver according to claim 1,wherein the pre-scan processing is performed in a state where the gainof an automatic gain control amplifier in a tuner is fixed.
 4. Thedigital broadcasting receiver according to claim 1, wherein it is judgedin the first means whether or not the received signal is of thepredetermined quality or more on the basis of judgment whether or notreceived power is more than a predetermined value.
 5. The digitalbroadcasting receiver according to claim 1, wherein the channelinformation include a receivable channel number, service information inthe case of a channel in digital broadcasting, and a distinction betweenthe channel in digital broadcasting and a channel in analogbroadcasting.
 6. A channel information registration processing method ina digital broadcasting receiver comprising: a first step of performingpre-scan processing for successively tuning in on channels previouslyset, to examine whether or not a received signal on each of the channelsis of a predetermined quality or more, and temporarily registering thechannel numbers of the channels on which the received signals are of thepredetermined quality or more in a storage device as receivable channelcandidates; and a second step of performing normal scan processing forsuccessively tuning in on the receivable channel candidates temporarilyregistered in the storage device in the first step, to acquire andregister necessary channel information.
 7. The channel informationregistration processing method in the digital broadcasting receiveraccording to claim 6, wherein the pre-scan processing is performed aplurality of number of times in the first step.
 8. The channelinformation registration processing method in the digital broadcastingreceiver according to claim 6, wherein the pre-scan processing in thefirst step is performed in a state where the gain of an automatic gaincontrol amplifier in a tuner is fixed.
 9. The channel informationregistration processing method in the digital broadcasting receiveraccording to claim 6, wherein it is judged in the first step whether ornot the received signal is of the predetermined quality or more on thebasis of judgment whether or not received power is more than apredetermined value.
 10. The channel information registration processingmethod in the digital broadcasting receiver according to claim 6,wherein the channel information include a receivable channel number,service information in the case of a channel in digital broadcasting,and a distinction between the channel in digital broadcasting and achannel in analog broadcasting.